It is presently known to cover aircraft with a synthetic material characterized in that it will shrink under the application of heat. Such a material is commercially available, one example being polyester cloth. An aircraft maintenance man can purchase the material in large quantities, assemble it over a frame portion of an aircraft by sewing or gluing sections together and attaching the same to the aircraft and thereafter heat shrinking the material so it will cling tightly to the aircraft frame portions. The heat shrinking may take place in a large oven or may be progressively applied as by heated irons or the like. The applied heat may range from 212.degree. to 425.degree. F.
After heat shrinking the material onto the aircraft, it is covered with a primer such as a phenoxy resin, coated with a filler, permitted to dry, and again coated with the filler which may also constitute a phenoxy type resin, and finally painted, for example, with a finish coating of enamel.
It has been found that when the foregoing method is employed, portions of the fabric material particularly when disposed against solid frame surfaces tend to develop pin holes. It is believed that these pin holes result from the capillary action of the solid surface area drawing away some of the coating material. In addition, any faults in the fabric weaving can result in the development of small openings or pin holes.
Development of pin holes as described above can result in poor appearance of the fabric in such areas. It is therefore important in covering aircraft in accord with present known methods to apply the successive coatings to the material after it has been shrunk onto the frame portion with meticulous care and at least two and preferably more coatings with suitable dope or resin are required.